An overall objective of this project is to reconstruct the invasiveness phenotype of Bartonella bacilliformis in Escherichia coli. Bartonella bacilliformis is the etiologic agent of a highly fatal hemolytic anemia which can result in death, if not treated. Historically, outbreaks of bartonellosis have been confined geographically to the western slopes of the Andes in Peru, Ecuador and Colombia. The Specific Aims of this proposal are the following: (1) Determination of host cell-type specificity for the bartonellae; (2) Thin-section electron microscopy of host cell- bartonellae interactions; (3) Construction of a Bartonella bacilliformis gene bank using a Bluescript plasmid expression vector; (4) Identification of E. coli clones that have the invasiveness phenotype using immunoscreening techniques and erythrocyte-binding assays; (5) Analysis of the structure of the invasiveness gene using restriction mapping and S1 nuclease analysis and (6) Determination of the nucleotide sequence at the 5' end of the invasiveness gene using dideoxy chain termination sequencing methodologies.